Re: bijective (was re: An Absurdly Brief Introduction to Unicode (was Re:

Date: Sat Feb 24 2001 - 09:16:53 EST

On 02/24/2001 02:17:13 AM Tom Lord wrote:

>"Bijective" describes a mapping between two sets. Every element of
>the source set ("the domain") is mapped to a unique element of the
>destination set ("the codomain")

The codomain is referred to by some as the "range".

>AND there are no left over elements
>in the codomain. A one to one mapping. An invertible mapping.
>"Injective" describes a mapping where every element of the domain maps
>to a unique element, but there may be left over elements in the

And the term "surjective" describes a mapping where every element of the
range is mapped onto - there are none left over, but it's possible that two
or more elements of the domain map to a single element of the range.

Thus, a bijection is both injective and surjective.

>This is now way off topic, so please think twice about following up.

Anything that helps us communicate better with one another is not off
topic, IMO.

- Peter

Peter Constable

Non-Roman Script Initiative, SIL International
7500 W. Camp Wisdom Rd., Dallas, TX 75236, USA
Tel: +1 972 708 7485
E-mail: <>

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